增强MRI肿瘤-皮下脂肪信号强度比值鉴别椎管内神经鞘瘤与脊膜瘤

Enhanced MRI tumor-subcutaneous fat signal intensity ratio for differentiation of intraspinal schwannoma and meningioma

目的观察定量分析增强MRI所示椎管内神经鞘瘤(IS)和脊膜瘤(SM)肿瘤-皮下脂肪信号强度比值(SIR)鉴别二者的价值。方法回顾性分析76例经病理证实的IS(IS组,n=43)和SM(SM组,n=33)患者的术前MRI,由2名医师(医师1和医师2)分别测量增强T1WI所示肿瘤及皮下脂肪信号强度(SI),并计算其SIR;比较组间SIR异,采用受试者工作特征(ROC)曲线评价SIR鉴别IS与SM的效能,计算相应曲线下面积(AUC)。结果医师1测得IS组及SM组的SIR分别为0.91±0.12和0.62±0.09,医师2分别为0.88±0.12和0.64±0.10,IS组的SIR均高于SM组(Z=-6.825、-6.368,P均<0.01)。ROC曲线显示,医师1及医师2测量的SIR鉴别IS与SM的AUC分别为0.959和0.928;医师1测量SIR的最佳临界值为0.77时,其诊断敏感度为86.05%,特异度为100%;医师2测量SIR的最佳临界值为0.79时,其诊断敏感度为81.40%,特异度为96.97%。结论增强MRI所示IS肿瘤-皮下脂肪SIR高于SM,据此可有效鉴别二者。

Objective To observe the differentiating value of quantitatively analysis of enhanced MRI tumor-subcutaneous fat signal intensity ratio(SIR)of intraspinal schwannoma(IS)and meningioma(SM).Methods Preoperative MRI of 76 pathologically confirmed IS(IS group,n=43)and SM(SM group,n=33)were retrospectively analyzed.The signal intensity(SI)of tumors and subcutaneous fat on enhanced T1WI were measured by two radiologists(radiologist 1 and radiologist 2),respectively.Then SIR of IS and SM were calculated and compared,and the efficiency of SIR for distinguishing IS and SM was evaluated using receiver operating characteristic(ROC)curve,the corresponding area under the curve(AUC)was calculated.Results SIR measured by radiologist 1 was 0.91±0.12 and 0.62±0.09 in IS and SM group,while 0.88±0.12 and 0.64±0.10 by radiologist 2,respectively,and SIR of IS group was significantly higher than that of SM group(Z=-6.825,-6.368,both P<0.01).ROC curve showed that the AUC of SIR measured by radiologist 1 and radiologist 2 in discriminating IS and SM was 0.959 and 0.928,respectively.Taken 0.77 as the optimal critical value of SIR,the diagnostic sensitivity and specificity of radiologist 1 was 86.05%and 100%,respectively.Taken 0.79 as the optimal critical value of SIR,the diagnostic sensitivity and specificity measured by radiologist 2 was 81.40%and 96.97%,respectively.Conclusion Tumor-subcutaneous fat SIR of IS on enhanced MRI was higher than that of SM,which could effectively differentiate IS and SM.